The major objectives of this proposal are to study the role of Campylobacter jejuni in the development of intestinal diseases in laboratory animals and man. This will be achieved, in part, through experimental studies designed in the ferret model to study the pathogenesis of Campylobacter-induced diarrhea. A thorough examination using in vivo and in vitro techniques of biochemical, histologic, histochemical, and immunologic changes which occur during development of Campylobacteriosis will allow an understanding of basic mechanisms which are causative in expression of the disease in animals and man. Our aims will center around the following areas of effort: Development of suitable animal model to establish histopathological and immunological markers for Campylobacter-induced bowel disease; identify by in vitro and in vivo techniques whether C. jejuni, isolated from man and animal, produces a toxin and/or whether invasiveness is an important component of the pathogenicity; detemine whether C. jejuni plays a causative role in proliferative intestinal disease in hamsters; and finally to study experimental variables which may be important in clinical expression of Campylobacteriosis in man and animals.